Clinical Radiology (1992) 45, 175-178

Ultrasonic Attenuation in Fibroadenoma of the Breast p. B- G U Y E R , K. C. D E W B U R Y , C. M. RUBIN, C. B U T C H E R , G. T. R O Y L E and J. T H E A K E R

Southampton and Salisbury Breast Screening Unit, Royal South Hants Hospital, Southampton Fifteen patients are described who attended out Breast Screening Programme, and were found to have sclerosed fibroadenomas, the imaging of which raised the possibility of carcinoma. In six of these a reflective zone between a mass lesion and distal acoustic shadowing might have been used to infer the benign diagnosis. Guyer, P.B., Dewbury, K.C., Rubin, C.M., Butcher, C., Royle, G.T. & Theaker, J. (1992). ClinicalRadiology 45, 175 178. Ultrasonic Attenuation in Fibroadenoma of the Breast

In the absence of radiologically visible calcification, acoustic shadow deep to a solid breast mass on ultrasound is a sign which may suggest that the mass is malignant (Kobayashi, 1981; Kubota et al., 1983; ColeBeuglet et al., 1983; Guyer and Dewbury, 1987). The occurrence of distal acoustic shadowing in benign breast disorders (Cole-Beuglet et al., 1983; Rosner and Blaird, 1985; Guyer and Dewbury, 1987) is well recognized, but remains a diagnostic challenge. In the first 2 years of our Breast Screening Programme (part of the NHS Breast Screening Programme) X-ray mammography has identified 15 non-calcified breast masses measuring 6 15 ram, in which ultrasound showed distal acoustic shadowing; in each instance this led to biopsy which revealed benign pathology. During this period 26 025 patients were screened. P A T I E N T S AND M E T H O D S All the patients were invited to the Breast Screening Programme and were therefore asymptomatic females aged between 50 and 64 years. Illustrative images are shown in Figs 1 4. The radiographs show a mass, generally of small size, normally but not always well defined, and uncalcified. In each instance there was sufficient doubt about the mass on X-ray mammography to recall the patient for assessment. Ultrasound was performed as part of the assessment, using a Siemens SL1 Ultrasound set with a 7.5 M H z transducer and a stand-off water bag. Each mass showed acoustic shadowing arising from the lesion. In nine patients the mass was well defined on ultrasound, with a sharp border definition; in five patients the mass was ill-defined, and in one patient the mass was obscured by the superficial portion of the acoustic shadow. When visible, the mass was invariably poorly reflective; in six patients it was separated at least in part from the acoustic shadow by a narrow, sharply defined, highly reflective zone (Figs lb, 2b). In the other lesions no such reflective zone was detectable (Figs 3 and 4). Because of the presence of a distal acoustic shadow all these lesions were excised after ultrasound localization with appropriate skin marking. Histology revealed that all the masses were fibroadenomas which differed from lesions normally encountered in younger women by Correspondence to: P. B. Guyer, Southampton and Salisbury Breast Screening Unit, Royal South Hants Hospital, Brinton's Terrace, Southampton.

virtue of widespread sclerosis of the stroma. All had well defined lobular margins, distinct from the surrounding breast tissue. The epithelial elements of these fibroadenomas were generally atrophic, consisting of slit-like spaces lined by flattened cells (Fig. 5). In several instances there was a little stromal calcification.

DISCUSSION The ultrasound features of fibroadenoma described in these 15 patients differ quite markedly from those usually described (Guyer and Dewbury, 1987), particularly in younger patients, where the masses are characteristically well defined, evenly echo-containing, and show no distal acoustic attenuation. The changes we have detected are probably the result of sclerosis of the fibroadenoma, perhaps occurring in parallel with the sclerosis of lobular connective tissue, a normal feature of breast involution, which increases with age. However, occasionally fibroadenomas of this type can occur in younger people, and conversely more cellular fibroadenomas can occur in older age groups; in both situations this is likely to precipitate consideration of biopsy on account of the unusual occurrence of these forms in these age groups, and the potential overlap with carcinoma. The suggestion that the production of fibrous tissue may be responsible for the distal acoustic shadow has been made by a number of authors (Calderson et al., 1975; Teixidor and Kazzan, 1977; Kobayashi, 1979; Harper et al., 1982; Cole-Beuglet et al., 1983). It should be noted that this central acoustic shadowing needs to be differentiated from the refractive edge-shadowing which can occur in any mass in the breast, and even on occasions from Cooper's ligaments. All these lesions were excised because malignancy could not be excluded. Detailed examination of the images showed that in six patients there was a thin, brightly reflective zone between the mass itself and the distal acoustic shadowing, a feature not described in breast carcinoma. This reflective zone appears to be due to the interface between the sclerosed fibroadenoma and the surrounding breast tissue. We believe that the presence of this brightly reflective zone might be used to suggest a benign diagnosis rather than carcinoma, and have started to adopt this policy. However, if this thin reflective zone is absent, the lesion is ultrasonographically indistinguishable from carcinoma and excision will have to be recommended.

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(a)

(b)

(b)

Fig. 1 - (a) Case I. Poorly marginated density on X-ray mammography, screen detected. (b) Case I. Ultrasound shows a well defined echo-poor mass with a lobulated outline. Deep to the lesion is acoustic attenuation separated fiom it by a narrow highly reflective zone. The well defined posterior margins of the lesion remain visible.

Fig. 2 - (a) Case 2. Radiograph showing a well defined mass deep to a scar from a previous biopsy. (b) Case 2. Ultrasound showing a well defined, echo-poor, ovoid mass with deep acoustic attenuation with a well defined, narrow highly reflective zone separating it from the mass. The well defined posterior margins of the lesion remain visible.

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(a)

(b) (a)

Fig. 4 - (a) Case 4. Radiograph showing a generally well defined rounded mass but with focal loss of border definition posteriorly. (b) Case 4. Ultrasound showing deep acoustic attenuation (the mass lies in the superficial aspect of the latter).

(b) Fig. 3 (a) Case 3. Radiograph showing an ovoid mass with well defined margins. (b) Case 3. Ultrasound showing a rounded mass which loses definition posteriorly as it merges with the posterior acoustic attenuation.

Fig. 5 Histology. A representative section showing part of a fibroa d e n o m a with a distinct lobular outline, composed of dense collagenous stroma enclosing slit-like epithelial spaces.

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Although small calcifications were seen on the histological s e c t i o n s o f a n u m b e r o f t h e s e f i b r o a d e n o m a s , n o n e w a s d e t e c t e d o n X - r a y m a m m o g r a p h y a n d it a p p e a r s t h a t calcifications play no significant part in the production of the acoustic, shadow in these lesions.

REFERENCES

Calderon, C, Vilkomerson, D, Mezrich, R, Etzold, FF, Kingsley, B & Haskil, M (1975). Differences in the attenuation of ultrasound by normal, benign and malignant breast tissue. Journal of Clinical Ultrasound, 4, 249 254. Cole-Beuglet, C, Soriano, RZ, Kuritz, AB & Goldberg, BB (1983). Ultrasound analysis of 104 primary breast carcinomas classified according to histologic type. Radiology, 147, 191-195. Guyer, PB & Dewbury, KC (1987). Sonomammography; An Atlas of Comparative Breast Ultrasound. pp. 16 18. J. Wiley, Chichester. Harper, P, Jackson, VP, Bies, J, Ransburg, R, Kelly-Fry, E & Noe, J (1982). A preliminary analysis of the ultrasound imaging character-

istics of malignant breast masses compared with X-ray mammographic.-appearances of the gross and microscopic pathology. Ultrasound in Medicine and Biology, 8, 365 368. Kobayashi, T (1979). Diagnostic ultrasound in breast cancer; analysis of the retrotumourous echo pattern correlated with sonic attenuation by cancerous connective tissue. Journal of Clinical Ultrasound, 7, 471 479. Kobayashi, T (1981). Current status of sonography for the early diagnosis of breast cancer. Abstract, Second International Congress on the Ultrasonic Examination of the Breast. p.45. British Lending Library, Boston Spa; Institute of Cancer Research. Kubota, AM, Tagima, T, Mitomi, T, Nanrik, M, Sakurai, I & Kobayashi, H (1983). Ultrasonogram of lntraductal-spreading Breast Carcinoma Ultrasonic Examination of the Breast. Eds. Jellins, J & Kobayashi, T, pp. 103 104. J. Wiley, Chichester. Rosner, D & Blaird, D (1985). What ultrasound can tell that clinical examination and X-ray cannot. Journal of Surgical Oncology, 28, 3O8 313. Teixidor, HS & Kazzan, E (1977). Combined mammographic-sonographic evaluation of breast masses. American Journal of Roentgenology, 128,409-417.

Ultrasonic attenuation in fibroadenoma of the breast.

Fifteen patients are described who attended out Breast Screening Programme, and were found to have sclerosed fibroadenomas, the imaging of which raise...
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